1. Field of the Invention
The present invention relates to an endoscope apparatus which enables the interior of an organic tissue to be observed by making use of light which has transmitted through the organic tissue.
This invention also relates to an endoscope light apparatus whereby an illumination from inside and outside a body cavity is possible.
2. Related Art Statement
In recent years, an endoscopic apparatus is widely used having an elongated probe portion inserted into body cavities to enable organs in the cavity to be observed. An endoscopic apparatus is also known which has an instrument channel through which an instrument is inserted as desired to effect a required treatment on an internal organ.
The conventional endoscope apparatus is designed to illuminate an objective organ in a body cavity and to collect the light reflected by the organ so as to form an image thereby allowing the organ to be observed. On the other hand, there is an increasing demand in the medical field for an apparatus which enables the user to observe not only the external surface of the organ in the body cavity but also other portions such as the reverse side of gastric wall, blood vessels in membrana, state of tumour and so forth.
In compliance with such a demand, Japanese Pat. Publication No. 21678/1979 discloses an endoscope apparatus which enables the user to observe an object by making use of light which has transmitted through an organic tissue.
However, an external illumination of a body with ordinary visible rays cannot provide sufficiently high level of light input to the endoscope because organic tissue usually has a small permeability or transmission factor to such ordinary visible rays. In consequence, the observation or the diagnosis is difficult to make due to insufficient input light. To eliminate this problem, it is necessary to employ a large-power light source which is large in size and weight and which consumes much electric power.
Medical diagnosis or observation is often conducted by making reference both to an image formed by light applied by an external light source and transmitted through the organic tissue and an image which is obtained by internal illumination provided by a light source inserted into a body cavity. Obviously, the quantity of the light from the external light source transmitted through the organic tissue varies depending on the position of observation. The conventional endoscope apparatus, however, is not designed to enable the ratio of intensity between the image formed by internal illumination and the image formed by external illumination. Thus, the user cannot optimize the ratio of intensity of images for the varying positions of observation.
The endoscope apparatus disclosed in Japanese Pat. Publication No. 21678/1979 also suffers from a disadvantage in that it cannot provide continuous image of object by the transmitted light because it is designed for photographing images in synchronization with flash light.
Japanese Pat. Publication No. 50576/1981, having a priority on Swedish Pat. Application No. 7613587-0, discloses an apparatus in which a light of a high level of lightness is applied to human body tissue and the image formed by this light transmitted through the human body tissue is photographed through an infrared filter. This apparatus, however, has a problem in that only limited portions of the human body can be observed because both the light source and the infrared film are disposed outside the human body.
Recently, there has also come to be extensively used an endoscope whereby organs within a body cavity can be observed by inserting an elongated insertable part into the body cavity or, as required, various therapeutic treatments can be made by using treating tools inserted through a treating tool channel.
Conventionally, a body cavity inside has been observed and therapeutically treated with such an endoscope by reflectively illuminating the body cavity inside tissue surface, such as the mucous membrane surface, with an illumination from the tip of the endoscope insertable part inserted into the body cavity and receiving and imaging the reflected light. However, with the conventional illumination, only the tissue surface can be observed.
Now, it is recently required to observe not only the surface of a body cavity inside tissue but also such tissue inside as the running state of veins below the mucous membrane or the penetrating range of a disease below the mucous membrane. Therefore, as shown in the publication of a Japanese Pat. publication No. 21678/1979, it is suggested to provide an outside illuminating mechanism provided outside a living body cavity to illuminate the living body from outside.
Also, a larynx stroboscope whereby the light of a flash lamp can be fed to an endoscope or the like is disclosed in the publication of a Japanese Pat. application laid open No. 87532/1986. However, this apparatus is not to feed the endoscope with a body inside illuminating light and body outside illuminating light.